Apparatus for conveying particulate solids

ABSTRACT

Linear vibratory motion is imparted to two mutually opposite plates, which are connected to each other. As a result, conveying impulses are applied to solid particles. To permit chemical or physical processes to be carried out with fluids flowing in cocurrent or countercurrent streams and to effect a transfer of material or heat at a high rate during the vibratory conveyance or to disintegrate or compact the solid particles, conveying pulses are imparted to the particles by both plates and the solids occupy in a state of rest only part of the free space between the two plates.

FIELD OF THE INVENTION

This invention relates to apparatus for conveying particulate solidsbetween two mutually opposite plates, which are connected to each other,wherein linear vibratory motion is imparted to the two plates to applyconveying impulses to the solid particles. My invention also relates toapparatus for effecting contact between a particulate solid and a fluidphase, e.g. to effect a reaction between them.

BACKGROUND OF THE INVENTION

It is known to convey particulate solids with vibratory conveyors. Mostvibratory conveyors comprise a vibratory conveyor trough, which isresiliently supported or resiliently suspended.

Vibratory motion is imparted to the trough by a force acting on thebottom of the trough in a direction which is at an acute angle to thelongitudinal direction of the trough. That force is generated byrotating unbalance members, eccentric members or electromagneticactuators and accelerates the trough in horizontal and verticaldirections. These accelerations result in an acceleration vector, whichincludes an acute angle with the direction of conveyance.

The vertical acceleration must exceed the acceleration due to gravity sothat the solid particles will separate from the trough and perform aballistic movement in the direction of conveyance. The troughs may beopen-topped or they may be covered so that an escape of dust will beprevented or chemical reactions with gases can be carried out. The coverdoes not influence the conveying motion of the solid particles. (OpenGerman Application DE OS No. 25 05 202, German patent publication DE ASNo. 22 07 225, Open German application DE OS No. 24 10 328, Open Germanapplication DE OS No. 24 10 344, Open German application DE OS No. 24 10345, U.S. Pat. No. 2,277,067, "Fordern und Heben", 1961, pages 317 to327).

The acceleration vector which includes an acute angle with the directionof conveyance may alternatively be produced in that the trough issubjected to separate accelerations in a vertical direction and in adirection which is parallel to the direction of conveyance. Thedirection of conveyance can be reversed by a reversal of the polarity ofthe vibrators acting in a direction which is parallel to the directionof conveyance (Open German application DE OS No. 19 42 332).

Such vibratory conveyor troughs may also be used to effect an upward ordownward conveyance up to a certain angle but they cannot be used for anupward or downward vertical conveyance. An upward vertical conveyancecan be effected only with helical troughs or in pipes provided withinternal fixtures (U.S. Pat. No. 4,140,215).

British patent specification No. 1,225,899 describes a conveyor whichconsists of two concentrical tubes whereby the annular space between thetubes is divided into a plurality of channels by means of radiallyarranged walls. The open lower end of the conveyor is immersed into abed of the material to be conveyed. Linear oscillations are imparted tothe conveyor parallel to the axis of the tubes and torsionaloscillations across the axis. The channels are filled in a state of restover the entire cross section with the material. By means of the angularaccelerations of the torsional oscillatory motions the material isforced towards the walls of channels and the material is moved upwardlyby means of the linear oscillations.

Vibratory conveyor troughs can mainly be used to convey materials. Theyare not well suited for carrying out chemical or physical processes inwhich gases are conducted in covered troughs to flow cocurrently orcountercurrently to the direction of conveyance because the transfer ofmaterial and heat takes place mainly on the surface of the bed of solidsand does not affect the entire cross section of that bed. A flow ofgases through the entire bed in transverse streams passing throughperforated bottoms disposed under the bed would require a relativelyhigh structural expenditure and in that case it is not possible toprovide for a countercurrent or cocurrent flow of the gases, which isoften desired.

OBJECTS OF THE INVENTION

It is the primary object of this invention to provide an improvedapparatus for conveying particulate solids whereby the drawbacks of theabove-described techniques are avoided.

Another object of the invention is to provide apparatus for effectinginteraction between a particulate solid and a fluid, especially a gas,with improved material and/or thermal exchange.

It is also an object of the invention to avoid these disadvantages andparticularly to permit a vibratory conveyance in which chemical orphysical processes are carried out which involve fluids flowingcountercurrently or cocurrently with respect to the direction ofconveyance and in which a transfer of material and heat is effected athigh rates or in which the solid particles are disintegrated orcompacted.

SUMMARY OF THE INVENTION

This object is accomplished in accordance with the invention in that theconveying impulses are applied to the solid particles by both plates andthe solids occupy in a state of rest only part of the free space betweenthe two plates.

In a direction which is normal to the plates, the solid particles are sohighly accelerated that they impinge on the opposite plate and that theyare accelerated by both plates in alternation. The acceleration which isrequired will depend on the spacing of the plates. The two plates aregenerally arranged in parallel planes and may be inclined at any angleor extend in vertical planes. The two plates are usually gastightlyconnected by side walls so that also in processes in which no gas issupplied no dust will escape. Chemical and/or physical processes can becarried out during the conveyance. For instance, the particles may becompacted or caused to agglomerate as they impinge on the two plates.

Thus it is important to the invention that the impetus in the conveyingdirection is transferred to the particles not only by the plate uponwhich the particles can rest under the action of gravity, but also bythe plate against which the particles are thrown against the action ofgravity and against which they are held by momentum/inertia after havingbeen cast thereagainst by the force impulse which acts counter to thegravitational force.

Unlike covered troughs, therefore, in which the cover plays no role inthe actual impetus to the particulate solid, the two-plate system of theinvention intentionally disposes the upper plate so that it willintercept the upwardly moving particles and will impart a velocitycomponent to them in the direction of conveyance.

According to a preferred further feature, vibratory motions at definedfrequencies and with amplitudes which are normal and parallel,respectively, to the direction of conveyance of the solid particles areimparted to the plates. If the vibrations are generated separately, themechanical stresses will be reduced and an effective control resultingin optimum handling and process conditions will be permitted.

According to another feature of the invention, the ratio of thefrequencies of the parallel and normal vibratory motions is about 2:3.With that ratio, each solid particle which has impinged on a plateremains in contact with that plate for a short time and will be carriedalong by the plates to some extent in the direction of conveyance beforethe particle is thrown back. In a countercurrent process that drageffect is particularly important because it opposes a backdrifting ofthe particles.

According to still another feature of my invention, the solids occupy ina state of rest less than 30% and preferably less than 10% of the freespace between the two plates. This produces particularly good results inchemical or physical processes.

Advantageously a fluid is conducted through the space between the platesin a cocurrent (codirectional flow) or countercurrent with respect tothe direction of conveyance of the solids. The fluid may consist ofgases, vapors or liquid and excellent transfer of material or heat canbe effected.

In this manner, chemical processes, such as the direct reduction of ironore to produce sponge iron, the devolatilization of oil shale or oilsand, and the roasting of sulfide ores etc., or the heating or coolingof the solids may be effected if the chemical composition and thetemperature of the fluids are properly selected. Whereas the solids mayalso be indirectly heated or cooled, this would require a largervibrating mass.

A plurality of charging openings and discharge openings for the solidsand a plurality of gas inlets and gas outlets in the plates or in wallsflanking the travel path may be provided so that the processes can becarried out under optimum conditions.

According to a preferred further feature at least one partition havingthrough holes for the passage of the accelerated solid particles isprovided between the plates. The through holes are spaced apart andextend transversely to the direction of conveyance and suitably consistof slots. In that arrangement, conveying impulses will be applied by twoopposite plates also to the smaller solid particles of solids having alarger particle size range even if the amplitude of the vibration thatis at right angles to the direction of conveyance is not otherwisesufficient to throw these particles from one of the outer plates to theother.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features and advantages of the presentinvention will become more readily apparent from the followingdescription, reference being made to the accompanying drawing in which:

FIG. 1 in diagrammatic side elevation shows a known vibratory conveyorthrough and indicates the motion imparted to the solid particles in thattrough;

FIG. 2 in diagrammatic side elevation shows a known vibratory conveyortrough designed to discharge solids from a bin;

FIG. 3 is a side elevation showing apparatus for carrying out theprocess according to the invention;

FIG. 4 is an elevation of the apparatus shown in FIG. 3, viewed from theleft;

FIG. 5 is a longitudinal sectional view showing the apparatus of FIG. 3and indicates how the solid particles and the gas move countercurrently;

FIG. 6 shows the conveying motion of the solid particles without a gasstream;

FIG. 7 indicates the conveying motion of the solid particles which areacted upon by a countercurrent gas stream; and

FIG. 8 illustrates the conveying motion of the solid particles in anapparatus provided with partitions.

SPECIFIC DESCRIPTION

In FIG. 1 I have diagrammatically shown a conventional open-top trough100 which is mounted as represented by the links 101 to undergo areciprocatory motion generally as represented by the arrow 102 asgenerated by a rotating imbalance weight represented at 103, a spring104 representing the restoring force against which the imbalance weightacts.

As will be apparent from the motion of the solid particles representedby the dotted line 105, an antigravitational impetus 106 is imparted tothe particles to lift them slightly from the floor of the trough, whilea horizontal component 107 is imparted to them to throw them forwardlyin a conveying direction from right to left, until the particles aredischarged at 108 over the downstream edge of the trough.

It will be apparent there that an antigravitational or levitatingimpulse is usually insufficient to cast the particles anywhere near theupper edge 109 and the trough so that even if the trough is covered, thecover does not contribute anything at all to the impetus in thedirection of the vector 109.

A similar action is generated by the vibrating trough 200 of FIG. 2which is disposed beneath a bin 210 and receives a controlled flow ofparticles as metered by a shutter arrangement representeddiagrammatically at 211. Here the trough is resiliently suspended, e.g.by springs 201, so as to have a downward inclination and is vibrated inthe direction of arrow 202 by the rotating imbalance weight so that anadvance component is in the direction of the vector 207 and a component206 of the force is imparted to the particles normal to the bottom ofthe conveyor trough, i.e. perpendicular to this bottom.

Here again, even if the trough is covered, there is no impetus suppliedby the cover to the particles in the direction of the vector 207.

In the apparatus shown in FIGS. 3-5 the two plates 1 and 2 are parallelto each other and are gastightly connected to each other by the sidewalls 3, 4. Resilient supports 5 are secured to the side walls 3, 4. Astiffener 6 is disposed under the plate 2. A vibrator 7 is secured tothat stiffener and generates vibrations which are at a defined frequencyand have an amplitude that is at right angles to the direction ofconveyance. A vibrator 8 is mounted on the end wall and generatesvibrations which are at a predetermined frequency and have an amplitudethat is parallel to the direction of conveyance. The solids are chargedthrough the flexible charging device 9 and are discharged through theflexible discharging device 10. Gas is blown by the blower 11 throughthe flexible feed conduit 12 to flow countercurrently to the solids andis withdrawn through the flexible withdrawing device 13. A deflectingplate 14 is provided between the device 9 for charging the solids andthe device 13 for withdrawing the gas.

In FIG. 6, f_(y) designates the frequency and y_(o) designates theamplitude of the vibration which is normal to the direction ofconveyance of the solid particles, and f_(x) and x_(o) designate thefrequency and the amplitude, respectively, of the vibration which isparallel to the direction of conveyance. Successive locations arerepresented at 6.1-6.12, respectively. Each of the amplitudes y_(o) andx_(o) acts in two directions. The frequency ratio f_(x) :f_(y) is 2:3.The distance between the plates 1 and 2 is designated A. Along the pathsection 6.1-6.2, the solid particle is in contact with the plate and isdragged to the right by the plate 2 owing to the horizontal movement ofthat plate. At point 6.2, that particle is thrown by the plate 2 to theplate 1 and impinges on the latter at 6.3 and is dragged by the plate 1to point 6.4 and is then thrown by the plate 1 to the plate 2.

In accordance with FIG. 7 where the locations are represented at7.1-1.12' and 7.1"-7.12", the paths of the solid particles are curved asa result of the action of the gas stream. The paths of the smallparticles are shown in the left-hand half of those of larger particlesin the right-hand half.

FIG. 8 shows the motion of particles between the plates 1, 2 and twopartitions 14, 15, which are formed with slots 16. The locations alongthe path are shown at 8.1-8.36. It will be sufficient if the amplitudex_(o) of the vibrations which are at right angles to the direction ofconveyance is so large that the impulses applied to the small particleswill cause them to impinge on the adjacent partition 14 or 15. Forinstance, if the impulse applied by the plate 1 at point 8.6 to a largeparticle is sufficient to throw it to point 8.7 of the partition 15whereas the impulse will not be sufficient to throw also smallerparticles to point 8.7, the smaller particles will impinge on the top orbottom surface of the partition 14 and will then be accelerated by thelatter.

In each of the structures shown in FIGS. 3, 6, 7 and 8, an initialimpetus is provided for the particles away from the lower surface uponwhich the particles come to rest and in the direction of another surfacejuxtaposed with the first sufficiently closely with this other surface,e.g. the upper surfaces 1 in FIGS. 3, 6 and 7 or the upper surface 1 andany of the surfaces of the partitions 14 and 15 above a surface 2, 15 or14 upon which the particles previously come to rest under the action ofgravity. When this upper surface intercepts the upwardly movingparticles it imparts to them an impetus in the conveying direction orleft to right in FIGS. 5-8, to supplement the impetus in this directionimparted by the resting surface from which the particles were thrown.Thus for each crossing of the gap between lower and upper surfaces,impetuses in the conveying direction are imparted at both extremities ofthe path and this applies as well to the passage from each upper surfaceto the lower surface onto which the particles fall.

The advantages afforded by the invention reside mainly in that the solidparticles are very effectively distributed throughout the cross section,high relative velocities between the solid particles and the fluid areobtained so that a very effective reaction can be achieved in aneconomical manner with fluids which flow countercurrently or cocurrentlywith respect to the solids, an effective heat transfer is permitted andthe particles can be compacted or agglomerated.

I claim:
 1. An apparatus for conveying a particulate solid whichcomprises:means defining a conveyance path for said solids including alower plate and an upper plate spaced above said lower plate anddefining a space therebetween containing particles of said solid in aquantity such that the solids occupy in a state of rest only part ofsaid space; means connected to said plates for imparting oscillationthereto with a component tending to throw said particles from said lowerplate against said upper plate and sufficient to impart to at least someof said particles sufficient motion to bring them into contact with saidupper plate, and a component in a conveyance direction along said pathwhereby said particles receive impetus in said conveyance direction uponeach contact with said upper and said lower plates; and at least onepartition in said space parallel to said plates and provided withopenings spaced apart in said conveyance directions such that saidpartition intercepts particles moving from one of said plate toward theother of said plates and additionally applies impetus in said conveyancedirection to the intercepted particles.